Treatment of rock asphalt



Patented Mar. 17, 1925.

urrso STATES PATENT ouste WILLIAM .E. BENTLEY, 0F DALLAS, TEXAS.

TREATMENT OF ROCK ASPHALT.

Application filed June 2,

To all whom it may concern:

Be it known that I, WILLIAM P. BENTLEY, a citizen of the United States, residing in the city of Dallas, county of Dallas, and State of Texas, have invented certain new and useful Improvements in the Treatment of Rock Asphalt, of which the following is a specification.

This invention relates to improvements in a method of treating rock asphalt, and refers more particularly to a processor method of treating native rock asphalt such as that mined in the southern States comprising a mineral such as rock of calcareous or siliceous origin containing a bitumen interspersed in the voids and pores of the rock.

Among the objects of the invention are to provide a composition having waterproof properties and susceptible of being worked and applied to surfaces for the purpose of insulating or waterproofing whileicold.

Other objects of the invention lie in the application of the substance as'a roofing or flooring purpose, covering for acid containers or reservoirs, water tanks,'its most useful purposehowever, being for paving purposes, its characteristics being such as to be admirably adapted for road coverings, side walks and other types of paving.

A further advantage of the process lies in the fact that the material can be laid in thin wearing surfaces that are stable, and do not creep and disintegrate even under heavjy traflic. Surfacing rtrom one-half to one and one-half inches in thickness laid cold does not wave or disintegrate, continuingto remain intact until worn out.

The invention has to do with the composition produced by disintegrating the rock and treating the bitumen contained therein to produce a mixture containing mineral rock and an asphaltic and bituminous substance, the latter having certain characteristics which maybe varied according to the purpose for which theflcomposition is tobe used. The varying of the character of the composition may be efl'ected without the use of heat.

Heretofore, it has been impossible to make cold rock asphalt mixtures using'a properly prepared asphaltic, semi-asphaltic or paraffin base fluxes, that is, material having .a fiashpoint in the vicinity of 350 F., or higher. The reason for this is that fluxes. from which the light constituents have been removed, will not mix and dissolve the cold process is complete.

- used, as in 1923. Serial No. 643,087.,

hard asphalt that is exposed subsequent to. the disintegration or pulverizing of the-rock asphalt.

It is essential that a solvent that will. op erate readily'on the cold bitumen in the rock, be present; In order to supply this neces sary solvent, a light distillate such as gasoline, kerosene, gas oil, naphtha, solar oil or the like, is added to the pulverized rock asphalt. The quantity of light distillate solvent will vary considerablywith the size of the particles in' which the rock asphalt has been brokemfor the reason that when the rock asphalt has been finely comminuted,

a greater surface area must be treated, and

more bitumen liquefied; This amount of light solvent needed, is not necessarilvan exact amount, for the reason that its function is to liquefy the bituminous or asphalt-i0 substance in the rock, only fora very lim-.

ited period of time. Under normal conditions, ten to thirty minutes will be sufficient time in which to perform this function, and it may then be evaporated without harm to the composition. Under Certainmonditioris ofdisintegration, it has been. found that one gallon of light distillate to one thousand pounds of rock asphalt is a satisfactory re- 1 lation.

This amount will necessarily varyalso with the varying of the percentage of bituminous or asphaltic" material containedm the rock asphalt.

In certain cases, it is necessary naturally to add asphaltic or bituminous material to the rock asphalt'to supplv thereto the desired percentage-of bituminous substance and impart the proper consistency. Should the asphalt in-the rock'be of high enough percentage, and of the proper-penetration for the pur-' poses for which it is to be used. the'composition which has been treated with the distillate may be compressed into finalformimmediately by rolling or tampin'g, and the In the event thatith'e asphalt in the rock be .too hard for the purposes for which thefcomposition is to be the bituminous limestones of Texas and Alabama, whose use .is limited practically to paving purposes, or should it be necessary to add asphalt to increase the percentage of bituminous matter in the mix ture, then the pulverized rock asphalt after the addition eta solvent, has supplied there to an asphaltic flux to increase the asphaltic content. That is, after adding the light disdesired consistency tillate which tends to dissolve and soften the bituminous material in the pulverized rock, a flux or asphalt having the characteristics necessary to bring the rock asphalt to the percentage, is added.

For example, Uvalde rock asphalt pulverized in any type of approved mechanical mixer, either of the pug mill type or a revolving concrete mixer type, may be treated with from two-thirds to one and one-third gallons distillate per one thousand pounds of the pulverized rock asphalt. After thoroughly mixing the distillate and rock asphalt, there isincorporated thereto, the desired asphalt, semi-asphaltic or paraffin base flux in a like manner to that in which. the solvent was added, either by spraying into the cylinder type of mixer, or by pouring or spraying .into the pug mill. It has been found that pouring the flux into the pug mill mixer is as effective as spra 111g, and

furthermore, if spraying is use gravity feed is sufficient.

The fluxes prior to being added to the pulverized rock asphaltarepreferably heated to temperatures in the neighborhood of the two materials late 200 .F., or more, depending upon their viscosities in order that they maybe in a thoroughly liquefied condition. The parafiin base flux known in Texas as Magnolia Uvalde rock asphalt flux has substantially the following specifications: a gravity ranging from 19 to 21 Baum, a. flashpoint in excess of or not less than 350 F., evaporation not over 5% when heated continuously for seven hours at 325 F. In utilizing this. type of oil and heating it to temperatures inexcess of 200 R, an excellent combination of the flux with the rock asphalt bitumen is'obtained, if the pulverized rock asphalt has been previously treated with a small quantity of light distillate. 'When using fluxes which are solid at ordinary temperatures, they should be heated sufliciently toconvert them into a relatively fluid condition. i

The result of combining a flux in this manner by first softening the bituminous material in' the rock, with a solvent, .is to cause the flux to intimately commingle and, permanently unite with the bitumen in the rock due to the-fact that this bitumen has been rendered temporarily liquid by the distillate solvent. Without the use of a solvent of this character, itv is impossible to make a satisfactory union of the heated fluxes with the cold bitumen in the cold rock as phalt, that is,-it is necessary to heat the asphalt-containing-rock sufiiciently to liquify the asphalt contained therein, and permit the unity of the asphalt and fluxes while are in a. liquid condition. the function. of the distilm merely temporary, but enables the It is clear that and proper asphaltio rock asphalt to be properly fluxed in a cold state, Whereas, it would otherwise be'necessary toheat the rock in order to efi'ect a proper union. I

Heretofore, it has been the common practice to add an unrefined oil to the rock asphalt and produce a softening of the as phaltic substance while the asphalt is in a cold and pulverized condition. Such oils however, vary greatly in gravity, viscosity, asphaltic content and volatile constituents, and normally have acertain amount of objec'tionable water contained therein. These factors being variable, naturally produce varying results which are objectionable in the production of uniform products or composition. It is also a fact that where the rock asphalt contains enough bitumen for paving purposes, but where this bitumen of too hard a consistency as in Uvalde rock asphalt, the use of an unrefined asphalt oil regardless of the resulting consistency must be restricted to an amount to prevent an excessof bitumen in the final product.

In the process explained, the amountct flux added to the pulverized asphaltic substance may be identical to that used in hot processes. Therefore, the bitumen content may be accuratelyv regulated and the consistency of the bitumen carefully controlled.

A further advantage of the addition of the fluxes to the cold rock asphalt is that the consistency of the bitumen can be made the same as in the hot asphalt processes. or even higher with an equal quantity of flux, 3 owing to the .fact that there is no hardeninn due to the heating process.

For Alabama roclr asphalt, which contains approximately 7% bitumen, a satis factory treatment would be about one gal- 195 ion of distillate per one thousand pounds of rock asphalt and flux while the rock asphalt is cold. the flux consisting of an asphalt which is solid at ordinary temperatures and which has been liquefied by heating.

A further advantage of the process is the fact that 'cold mixed pavements yvill be in all respects verysimilar and as uniform as the pavements that are made by methods of heating the rock asphalt. Treating cold in this manner eliminates the obiectionable features accompanying the heating-of the rock asnhalts by a fuel oil blast directed on the inside or to the exterior of'the cylinder in which the rock asphalt is contained. The working'temperature inside of the cylinders frequently runs as high as 1800" F., resulting in a.- loss of valuable properties in the native bitumen and rock asphalt, factors which are totally eliminated by the use of a distillate solvent and the addition of a flux as explained.

A proper flux is a residuum conforming to specifications as to gravity, asphalt con tent. high flash and low evaporation.

In place of adding the distillate and flux separately, it may be desirable-to add the distillate to the flux and incorporating the combination tothe cold pulverized rock'asphalt in a similar manner to that explained in connection with the adding of the. distil late or flux previously.

Fetloiving'areisamples made of characteristicf combinations, which give satisfactory results for paving. It is understood-however that these are particularly given' as eX-' amples. and in no way tend to limitthe scope of the invention, as innumerable satisfactory combinations may be utilized for the different uses to which the composition may he applied. 4

i Pulverized rock asphalt. Kind and quantity distillate. F1ux.

Gals.

3000..- 300D Gasollneigal l The salient elements of theinv entionconsist in pulverizing or breaking up the mineral rock asphalt, and-while in a broken up. state adding a liquid solvent thereto to softenthe bituminous or asphaltic substance'con- Rn tained in the rock, and incorporating with the pulverized or broken up material a flux-v used in the future, thus permitting the transportingoi the material from place toplace and .eli mina'ting the necessity of heating and reheating whenever iv it is to be ,us ed.

I claim as my invention: i i LA process forfifiaking a composition, consisting i i mixing ,less than 5% by weightjojt an atmospherically volatileliquefierv with disintegrated .bitumen-' bituminous containingrock, and separately adding to this mixtureless than by Weight of anormally adhesive viscous flux andcontrollin'gthe penetration and bituminous content of the final product by regulating the viscosity andamount of flux. v y Aproeess for mak'ng a road composi tion, consisting in pulverizing unheated biless than 5% Oran atmospherically volatile liquefier, and separately adding to this mixture a. normallyadhesive flux, causing said flux to permanently unite with the naturally contained bituminous material, and controlling the bituminous content in the final product by regulating the amount of flux.-

A process formakin'g a road composition consisting in pulverizing unheated biless than of an atmospherically volatile liquefier and separately adding to this mixtrre less than. 10% of a normally adhesive viscous flux, and accurately regulatingthe penetration of the bitumen in the final com- .position by controlling the viscosity of the' flux. r

-V a. A process t'or making a road composition consisting in.pulverizing unheated bi tuinen-containing rock, mixing therewith an 'atmospheri-cally volatile liquefier, and separately adding to this mixture liquid viscous flux in heated condition and controlling the percentage ot-bituminous material and consistency of bitumen in the final composition,

tumen-contaimngrock, mixing therewith 9 tumen-containing rock, mixing therewith by regulating the quantity and viscosity or the flux. 4 -Y I VVILLI'AM P, BENTL EY. 

